Method of fabrication of semiconductor integrated circuit device

ABSTRACT

The conveyance of wafers in bays (equipment groups) of a clean room is performed by RGVs (Rail Guided Vehicles) that linearly travel on conveying rails ( 3 ) laid on the floor of the clean room at high speed. A structure is adopted wherein a conveying area over which the RGV travels, is separated from a human working area by a compartment (partition) ( 4 ), and a human does not enter the conveying area upon operation of a line.

TECHNICAL FIELD

[0001] The present invention relates to a technology for manufacturing asemiconductor integrated circuit device, and particularly to atechnology effected if applied to a wafer conveying system employed in asemiconductor production line.

BACKGROUND ART

[0002] With multiproduct formation of semiconductor products andshort-living of a cycle time, a semiconductor production line isrequired to further shorten TAT (Turn Around Time) and shorten a processprocessing time. With an increase in diameter of a semiconductor wafer(hereinafter called wafer), the weight per wafer is on the increase.Therefore, automatic processing of wafer conveyance by a machine becomesan essential requisite for a semiconductor production line that handlesa wafer having a diameter of 300 mm.

[0003] In the semiconductor production line that copes with the 300-mmwafer, various manufacturing apparatus are generally divided intoequipment groups called bays, which in turn are placed within a cleanroom in bay units. Therefore, a wafer automatic conveying system is alsoconfigured with being divided into elements (components) such asbay-to-bay conveyance, bay-in conveyance and stockers correspondingly.

[0004] Of these components, a ceiling conveying method called an OHS(Over Head Shuttle) is generally used in the bay-to-bay conveyance. Aconveying vehicle called a RGV (Rail Guided Vehicle) that automaticallytravels on a track, a conveying vehicle called an AGV (Automatic GuidedVehicle) that automatically travels on a non-track, or OHT (Over-HeadHoist transport) corresponding to one ceiling conveying method, or thelike is used in the bay-in conveyance.

[0005] The stockers are disposed in relay locations between thebay-to-bay conveyance and the bay-in conveyance respectively. Each waferaccommodated in wafer conveying means (wafer carrier) is temporarilyheld in its corresponding stocker, after which it is conveyed into thebay. As the 300-mm wafer conveying means (wafer carrier), one is usedwhich is called a FOUP (FOUP: Front Opening Unified Pod) wherein a wafercassette and a pod (box) are unified to make it possible to convey aplurality of sheets of wafers in a sealed state, or one is used which iscalled an open cassette (Open Cassette: OC) wherein a wafer is exposedinto a clean room.

[0006] Incidentally, the wafer conveying system for the semiconductorproduction line that copes with the 300-mm wafer has been described in“Monthly Semiconductor World”, Press Journal Inc., issued on Dec. 20,1997, pp. 131-149, and the like.

DISCLOSURE OF THE INVENTION

[0007] According to the investigations of the present inventors, thewafer conveying system for the 300 mm-wafer adaptable semiconductorproduction line which has heretofore been put forwarded, has encountereddifficulties in realizing the shortening of a wafer conveying time andan improvement in line availability factor, and particularly has createda bottleneck in TAT shortening of each product short in delivery perioddue to the following problems.

[0008] (1) A ground travel type wafer conveying system introduced in asemiconductor production line up to a 200 mm wafer generation needed torestrict the maximum traveling speed and take safety measures providedby industry against conveying vehicles (AGV and RGV) in a conveying areain order to allow the conveying vehicles and humans to coexist with oneanother. Since, however, the safety measures interferes with an increasein the traveling speed of each conveying vehicle in the conveying systembased on the presumption that the conveying vehicles and humans coexistwith one another, the shortening of a wafer conveyance time isrestricted.

[0009] (2) A ground travel type wafer conveying system using AGVs andRGVs needs to perform the cooperative service of a plurality ofconveying vehicles and construct a system (algorithm) for realizingcomplex conveying routes in order to enhance the capability ofconveyance of each wafer. Since, however, the time required to wait foreach conveying vehicle frequently occurs in such a complex system, it isdifficult to realize an improvement in line availability factor.

[0010] An object of the present invention is to provide a waferconveying system capable of shortening a wafer conveying time.

[0011] Another object of the present invention is to provide a waferconveying system capable of improving an availability factor of asemiconductor production line.

[0012] A further object of the present invention is to provide a waferconveying system capable of shortening a wafer processing time.

[0013] The above, other objects and novel features of the presentinvention will become apparent from the description of the presentSpecification and the accompanying drawings.

[0014] Summaries of representative ones of the inventions disclosed inthe present application will be described in brief as follows:

[0015] The present invention is aimed to, upon formation of integratedcircuits on wafers by using a semiconductor production line in which aplurality of single wafer processing type semiconductor manufacturingapparatuses are partitioned into a plurality of bays (equipment groups)and installed within a clean room, and a wafer conveying systemincluding bay stations which perform bay-to-bay conveyance and bay-inconveyance and relay them, perform the wafer bay-in conveyance by RGVseach of which moves forward and backward alternately along a singlelinear conveying rail provided within a conveying area separated from ahuman working area.

[0016] The conveying rails on which RGVs linearly travel, arerespectively shared between a plurality of the RGVs according to therequired amount of conveyance of each wafer and the mode of itsconveyance, and travelling areas of the plurality of RGVs arerespectively mutually separated from travelling areas of other RGVs.

[0017] The bay-in conveyance of each wafer and the bay-to-bay conveyancethereof are performed in a state of each wafer being sealed in a FOUP.

[0018] By reducing the number of wafers accommodated in the FOUP, theprocessing time per wafer is shortened..

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is an overall plan view showing a wafer full-automaticconveying system for a semiconductor production line illustrative of oneembodiment of the present invention;

[0020]FIG. 2 is a plan view illustrating part of the conveying systemshown in FIG. 1;

[0021]FIG. 3 is a plan view for describing an interlock control methodof the conveying system shown in FIG. 1;

[0022]FIG. 4 is a plan view depicting wafer conveying areas and workingareas for the semiconductor production line shown in FIG. 1;

[0023]FIG. 5 is an explanatory view of a wafer transfer method suitablefor use in each manufacturing apparatus installed in the semiconductorproduction line shown in FIG. 1;

[0024]FIG. 6 is an explanatory view of a wafer transfer method suitablefor use in each manufacturing apparatus installed in the semiconductorproduction line shown in FIG. 1;

[0025]FIG. 7 is an explanatory view of a wafer transfer method suitablefor use in each manufacturing apparatus installed in the semiconductorproduction line shown in FIG. 1.; and

[0026]FIG. 8 is a view for describing another embodiment of asemiconductor production line of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0027] Embodiments of the present invention will hereinafter bedescribed in detail based on the accompanying drawings. Incidentally,members having the same functions in all the drawings for describing theembodiments are respectively identified by the same reference numeralsand their repetitive description will be omitted.

[0028]FIG. 1 is an overall plan view showing a wafer full-automaticconveying system for a semiconductor manufacturing or production line,which is associated with a wafer having a diameter of 300 mm, and FIG. 2is a plan view showing part (area corresponding to 3 bays) of theconveying system.

[0029] Various manufacturing apparatuses 1 such as a thermal treatmentequipment, an ion implantation system, an etching system, a depositionapparatus, a cleaning equipment, a photoresist coating apparatus, anexposure system, etc. employed in semiconductor manufacture are dividedinto plural bays (equipment groups) and placed within a clean room CR.The wafer conveying system lying within the clean room CR corresponds tosuch placement and is constituted by bay stations (stockers) BS whichperform bay-to-bay conveyance and bay-in conveyance and relay them.

[0030] The bay-to-bay conveyance is performed by an OHS (Over HeadShuttle) for conveying each wafer via a track 2 mounted to a ceiling inthe clean room CR. On the other hand, the bay-in conveyance is performedby RGVs (Rail Guided Vehicles) (wafer conveying means) 11 that travel onconveying rails 3 laid on the floor of the clean room CR. The conveyingrails 3 are shared among a plurality of the RGVs 11 according to therequired amount of conveyance of each wafer and the form or mode of itsconveyance. Each of the RGVs 11 is capable of running or travelling at ahigh speed equivalent to twice or more the speed (60 m/s) of an AGV(Automatic Guided Vehicle) that travels on a non-track.

[0031] The wafer conveying system according to the present embodimentresides in that the conveying rails 3 are respectively laid straightalong the bays to thereby set the travelling of the RGVs 11 movedbetween the apparatuses as simple linear reciprocating motions. Limitingthe travelling of the RGVs 11 to the linear reciprocating motions makesit possible to realize space saving for each conveying area andeliminate the need for construction of an algorithm for realizingcomplex feeding or conveying paths or routes. Further, even when thelayout of the manufacturing apparatuses 1 is changed later, the presentembodiment is capable of flexibly coping with it.

[0032] Also in the wafer conveying system according to the presentembodiment, the travelling areas of the respective RGVs 11 arerespectively separated by compartments (partitions) 4, and one baystation BS is assigned to one RGV 11. Thus, since there is no mutualinterference with other RGVs 11 that respectively share the use of theconveying rails 3, the waiting times for other RGVs 11 do not occur,thus making it possible to enhance production efficiency of the wholeproduction line. By assigning one bay station BS to one RGV 11, thewafer conveyed to the bay station BS via the OHS can be quicklydelivered to the RGV 11. Namely, since the wafer can be deliveredwithout via a stocker intended for temporary storage of the wafer, thetime required to feed the wafer can be shortened. A size reduction inthe bay station BS is also enabled and the space saving in clean roomcan be realized.

[0033] Further, the wafer conveying system according to the presentembodiment takes a structure wherein the conveying areas in which theconveying rails 3 are laid, are surrounded by compartments (partitions)5, and doors 6 are respectively provided between the adjacentmanufacturing apparatuses 1, thereby separating the conveying areas andhuman working areas and preventing humans from entering into theconveying areas upon operation of the line. The doors 6 provided amongthe apparatuses are respectively connected to an interlock controlsystem for the RGVs 11 such as shown in FIG. 3. When the door 6 isopened, the corresponding RGV 11 stops at once so that the safety of thehuman that entered the conveying area carelessly can be ensured. Whenthe human enters the corresponding conveying area with a view ofperforming maintenance or the like of the manufacturing apparatuses 1and the RGVs 11 upon non-operation of the line, the human enters theconveying area after having unlocked the door 6.

[0034] Thus, since the wafer conveying system according to the presentembodiment is designed on the presumption that the conveying areas donot coexist with the humans therein, safety measures (such as theinstallation of running indicator lights, safety sensors) for the RGVs11, which are provided by industry, can be relaxed. It is also possibleto increase the travelling maximum speed of each RGV 11 and therebyshorten the conveying or carrier time. Since the travelling of the RGV11 is limited to the linear reciprocating motion, the factors that theRGVs 11 are decelerated at curves and branches or the like areeliminated. Therefore, the travelling of each RVG 11 while maintainingthe maximum speed up to the intended place or location, is enabled. Evenin this point, the conveying time of each wafer can be shortened.

[0035] Since the feeding of the wafer at high speed is enabled, theinfluence of the waiting time for each RGV 11 on the productivity of thewhole production line is reduced. Therefore, it is also feasible tocause the RGVs 11 to standby for the purpose of conveyance of a specificlot, for example. The TAT of each product in which a period from thereceipt of an order to the delivery is short, can be significantlyshortened.

[0036] Since the wafer's conveying areas and the human working areas arecompletely separated from one another in the wafer conveying systemaccording to the present embodiment, routes taken where newmanufacturing apparatuses 1 are carried in the clean room and amortizedmanufacturing apparatuses 1 are carried out of the clean room, arerespectively provided on the sides opposite to the conveying areas withthe manufacturing apparatuses 1 interposed therebetween as shown in FIG.4. Since the wafer conveying system according to the present embodimentis capable of achieving space-savings for the conveying areas, thecarry-in/carry-out routes of the apparatuses can be widely ensuredcorrespondingly. Also human operations such as a terminal operation ofeach apparatus, its monitoring, maintenance (chamber cleaning, partreplacement, repairing, parameter's adjustments) of each apparatus canalso be performed here.

[0037] The semiconductor production line according to the presentembodiment is designed on the presupposition that all steps in a waferprocess are processed by a single wafer processing system.

[0038] Upon wafer conveyance between the bays and within the bays, awafer cassette and a pod (box) are integrated into one, and a FOUP(FOUP: Front Opening Unified Pod) capable of accommodating about 25sheets of wafers at the maximum in a sealed state is used. Since theFOUP is a wafer carrier for conveying each wafer in the sealed state, acleanliness factor of each wafer can be held to Class 1 or less withoutdepending surrounding environments. Thus, since the whole clean room CRmay not be cleaned up to Class 1 or less, the facility costs of theclean room CR can be reduced and the degree of freedom of design can beenhanced. Since the FOUP is capable of reliably fixing each wafer ascompared with an open cassette for accommodating each wafer in a stateof being open to the clean room CR, the FOUP is high in impactresistance and suitable for high-speed conveyance.

[0039] The FOUP having accommodated the wafers therein is fed to itscorresponding bay station BS in a predetermined bay by the OHS mountedto the ceiling in the clean room CR, where it is mounted to thecorresponding RGV 11 and conveyed to the manufacturing apparatus 1 inthe bay. The FOUP is provided with a door at the front facing themanufacturing apparatus 1 and conveys one wafer into the apparatus whilethe door is being brought into close contact with a loader of themanufacturing apparatus 1. Each manufacturing apparatus 1 is providedwith a door opener for opening/closing the door of the FOUP. Thus, asthe configuration of each load lock chamber of the manufacturingapparatus 1, there is adopted a system for transferring wafers 10 viaindividual conveying robots 9 provided between a plurality of FOUPs 7and load lock chambers 8 as shown in FIG. 5 by way of example withoutadopting a system wherein a plurality of chambers are disposed radialaround a conveying robot with the conveying robot as the center as inthe prior art. Alternatively, wafers 10 may be transferred viaindividual conveying robots 9 provided between a plurality of FOUPs 7and manufacturing apparatuses 1 as shown in FIG. 6, or wafers 10 may betransferred via conveying robots 9 provided between one FOUP 7 and aplurality of manufacturing apparatuses 1 as shown in FIG. 7.

[0040] The wafer carried in each manufacturing apparatus 1 is subjectedto a predetermined single wafer processing and thereafter unloaded fromthe manufacturing apparatus 1 and accommodated in the FOUP. Then thewafer is mounted in the corresponding RGV 11 and conveyed to anothermanufacturing apparatus 1. The wafer in which a process in apredetermined bay has been completed, is accommodated in the FOUP andconveyed to the bay station BS and further fed to a bay station BS of abay in the next process by an OHS, followed by being subjected to thenext single wafer processing.

[0041] According to such a configuration as described above, a lotconfiguration of each product (wafer) can be substituted with a minorityorganization in which 25 sheets/FOUP is changed to 13 sheets/FOUP, byreplacing the conventional batch process facility for processing, forexample, 25 or more wafers in a batch with a single wafer facility. As aresult, the processing time per FOUP can be shortened. By making anextremely minority organization like 1 to 3 sheets/FOUP, the TAT of eachproduct short in delivery period can be significantly shortened.

[0042] While the invention developed above by the present inventors hasbeen described specifically based on the embodiments, the presentinvention is not limited to the embodiments. It is needless to say thatvarious changes can be made thereto within the scope not departing fromthe substance thereof.

[0043] As shown in FIG. 8 by way of example, a sub production lineconstituted by a group of manufacturing apparatuses high in the usefrequency is provided except for a main production line and used foreach product short in a delivery period, for example, thereby making itpossible to significantly reduce the TAT.

[0044] According to the production line of the present invention, theeffect of shortening the TAT becomes the maximum where all steps in thewafer process are processed by single wafer processing system. However,some manufacturing apparatuses short in cycle time may be constituted bybatch type manufacturing apparatuses.

[0045] The conveying rails may not be laid linearly in each area inwhich high-speed conveyance in the clean room is not required. A mutualentry of plural RGVs, curve running, offshoot running, low-speedrunning, etc. may be utilized in combination.

[0046] The number of bay stations assigned to one RGV is not limited toone. A plurality of bay stations may be allocated. Large-capacity baystations each equipped with a wafer stocker function may partially beplaced.

[0047] By making it possible to move compartments (partitions) forseparating conveying areas and working areas, the area of each humanworking area relative to its corresponding conveying area can also bechanged freely.

[0048] Even as to the number of manufacturing apparatuses assigned toone RGV, different numbers may be allocated every bays according to thecapabilities of the manufacturing apparatuses without making the numberthereof identical among all the bays. It is also possible to providesuch flexibility that their allocation can be changed with ease duringoperation.

Industrial Applicability

[0049] Effects obtained by representative ones of the inventionsdisclosed in the present application will be explained in brief asfollows:

[0050] Since the wafer conveying time can be shortened, the TAT of asemiconductor product short in delivery period can be shortened.

[0051] Since the availability factor of a semiconductor production linecan be improved, the TAT of a semiconductor product short in deliveryperiod can be shortened.

DRAWINGS

[0052]FIG. 3

[0053] CONVEYING AREA

[0054] RELAY

[0055] RGV CONTROLLER

[0056]FIG. 4

[0057] CONVEYING AREA CONVEYING AREA

[0058] CARRY-IN/CARRY-OUT ROUTE OF APPARATUS, HUMAN WORKING AREACONVEYING AREA CONVEYING AREA CONVEYING AREA

[0059]FIG. 8

[0060] LITHOGRAPHY APPARATUS, ETCHING APPARATUS, LITHOGRAPHY APPARATUS

[0061] THERMAL OXIDATION APPARATUS, CVD APPARATUS, LITHOGRAPHYAPPARATUS, ETCHING APPARATUS, CVD APPARATUS, LITHOGRAPHY Apparatus

1. wherein the tracks for the RGVs are laid on substantially straightlines:
 3. (Deleted)
 4. (Deleted)
 5. (Amended) The fabrication methodaccording to claim 2, wherein the bay-to-bay conveyance of the wafers isperformed via a track mounted to a ceiling in the clean room. 6.(Deleted)
 7. (Deleted)
 8. (Deleted)
 9. (Deleted)
 10. (Deleted) 11.(Deleted)
 12. (Deleted)
 13. (Deleted)
 14. (Deleted)
 15. (Deleted) 16.(Deleted)
 17. (Deleted)
 18. (Deleted)
 19. (Deleted)
 20. (Deleted) 21.(Amended) The fabrication method according to claim 5, wherein thediameter of the wafer is greater than or equal to 300 mm.